1. Field of the Invention
The present invention relates to an authenticity determination method, apparatus and program, and more particularly to: an authenticity determination method for determining the authenticity of a solid object having a random readable unique characteristic distributed along the surface thereof; an authenticity determination apparatus applicable to the authenticity determination method, and a program for causing a computer to function as the authenticity determination apparatus.
2. Description of the Related Art
Recently, along with improved performance of copiers and printers, incidences are increasing of forged copies of banknotes and securities printed illegally by copiers and printers. Against such a background, to suppress illegal use of fakes and forged copies, there is a strong demand for establishment of technology capable of determining with high precision the authenticity of various paper documents (including, aside from banknotes and securities, for example, passports, deeds, certificates of residence, birth certificates, insurance policies, warranties, confidential papers, etc.).
A technology for determining the authenticity of paper documents is disclosed, for example, in Japanese Patent Application Laid-Open (JP-A) No. 2000-094865, in which a luminous substance, emitting light in an intrinsic wavelength region when illuminated with light in a specific wavelength region, is applied on a sheet of paper with local differences in the degree of opacity. Then light in the specific wavelength region is illuminated thereon, and the light emitted from the luminous substance is detected by a photo sensor, and authenticity is judged. Japanese Patent Application National Publication (Laid-Open) No. 2002-518608 discloses a technology for integrating a conductive marker substance (transparent conductive polymer, or conductive pigment, or combination thereof) with a paper web for document, security or banknotes.
JP-A No. 2000-146952 discloses a technology of analyzing the frequency of image data obtained from the light passing through or reflected by sample paper material, and deriving integrated data for plural wavelength regions from the data after frequency analysis, and determining the correlation with integrated data of a standard paper sample, thereby determining if the sample paper material is the same as the standard paper sample or not.
Japanese Patent Application Publication (JP-B) No. 6-16312 discloses a technology of dividing a specified area of a tag T into a multiplicity of square regions by making use of random changes of transparency of paper due to randomness of texture of fibrous material forming paper, detecting the transparency of six square regions selected at random, recording the detected transparency together with the addresses of the individual square regions as information. Then, by detecting the transparency of individual square regions specified by the recorded information when determining the authenticity, authenticity can be determined by comparing the detected results with the transparency indicated by the recorded information.
However, the technologies disclosed in JP-A No. 2000-094865 and Japanese Patent Application National Publication (Laid-Open) No. 2002-518608 are intended to prevent forging by applying a specific substance to paper to determine authenticity, and it is costly and a special device is needed for detecting the specific substance for determining the authenticity.
The technology disclosed in JP-A No. 2000-146952 is a technology for identifying paper by making use of the texture given to paper in the paper making process, or periodicity of patterns formed by paper making wires or the like. However when this technology is applied in authenticity determination of paper documents, if the same paper as in the manufacturing lot of the original paper document is obtained by someone of malicious intent, and copies of the content of the original made, these copies may be falsely judged to be original.
On the other hand, the technology disclosed in JP-B No. 6-16312 makes use of random changes of transparency of paper due to randomness of texture of fibrous material forming paper, and it is not necessary to provide the paper with special properties, and individual papers can be distinguished even if the papers are from the same manufacturing lot. In this technology, however, since authenticity is determined by comparing the transparency of a very small region of paper, it is highly possible that authenticity may be determined incorrectly if the position or direction of reading of the region on the paper is even only slightly different between reading when recording information and reading when determining the authenticity. Detection value of transparency is also influenced by not matching the quantity of light source when reading, or discoloration of paper due to ultraviolet rays or the like. The technology disclosed in JP-B No. 6-16312 also does not consider lowering the precision of determining the authenticity due to such events, and the precision of determination of authenticity is not sufficient.